When I was at Tulane in the 1970’s we used the 1 credit per course system, as opposed to the credit-hour system that is more common, and currently in use by Tulane. Not sure when they switched. But back then, just as @ucbalumnus says, they considered 1 credit unit to be equivalent to 4 credit hours at other schools, even though we only met for three 50 minute sessions or 2 75 minute sessions a week for most courses. So if you took a summer school course worth 3 credit hours at WUSTL, for example, you only got 3/4 of a credit unit in transfer at Tulane. Labs were not listed separately but we just considered part of the course. I happened to be in their honors chemistry course freshman year, and we had lab from 1-8 PM every Wednesday! Still one credit total for the course + lab. The non-honors lab was only 2 hours a week.